Motor and electronic apparatus using the same

Abstract

A rotor 14 is rotatably disposed around a stator 13 that is provided with a plurality of magnetic poles 13a. The inner circumferential face of the rotor is provided with a magnet 15 on whose face opposing the stator main magnetization is performed, and on whose face opposing the substrate FG magnetization is performed. The outer circumferential ends of the magnetic poles of the stator are provided with extended portions 13b and 13c that vertically extend from the magnetic pole base 13d. A face of the substrate opposing the rotor is provided with a FG pattern 19 opposing the magnet 15. The FG pattern is disposed on an outer side in a radial direction of the outer circumferential face of the stator. When an angle formed by a straight line connecting a central position in the radial direction of the magnet and a central position in the radial direction of the FG pattern with respect to a central axis of a driving shaft is taken as θ, and an angle formed by a direction of the FG magnetization with respect to the central axis of the driving shaft is taken as A, 0 degree<A≰θ is satisfied. Accordingly, it is possible to improve the precision in detecting the rotational speed by reducing noise superimposed on the FG signal, while securing a high driving efficiency.

1. A motor, comprising:
 a stator that is mounted on a substrate and on whose outer circumference a plurality of magnetic poles are arranged at a first predetermined interval; and 
 a rotor that is rotatably disposed around the stator; 
 wherein an inner circumferential face of the rotor is provided with a magnet, 
 main magnetization is performed on a face of the magnet opposing the stator to have opposite polarities at a second predetermined interval in a direction opposing the stator, and FG magnetization is performed on a face of the magnet opposing the substrate to have opposite polarities at a third predetermined interval, 
 each of outer circumferential ends of the plurality of magnetic poles of the stator is provided with a first extended portion that extends from a magnetic pole base to the substrate side, and a second extended portion that extends from the magnetic pole base to a side opposite the substrate side, 
 a face of the substrate opposing the rotor is provided with a FG pattern including a main pattern and a cancellation pattern such that the FG pattern opposes the magnet, 
 the FG pattern is disposed on an outer side in a radial direction of an outer circumferential face of the stator, and 
 in a cross-section along a plane including a central axis of a driving shaft coupled to the rotor, when an angle formed by a straight line connecting a central position in the radial direction of the magnet and a central position in the radial direction of the FG pattern with respect to the central axis of the driving shaft is taken as θ (θ<90 degrees), and an angle formed by a direction of the FG magnetization with respect to the central axis of the driving shaft is taken as A (A<90 degrees), 0 degree<A≦θ is satisfied. 
 
     
     
       2. The motor according to  claim 1 , wherein, in the cross-section along the plane including the central axis of the driving shaft coupled to the rotor, a central position in the radial direction of the main pattern is disposed on an outer side in the radial direction of an outer circumferential face of the magnet. 
     
     
       3. An electronic apparatus, comprising:
 a main body case; 
 a driven member that is provided in the main body case; and 
 a motor that is coupled to the driven member; 
 wherein the motor is the motor according to  claim 1 .